GUIDE TO WATER CONSERVATION
Plumbing fixtures that use less water have been a solution for water conservation for decades, and some have become standards. When Washington, DC, was one of the first to require low-flow toilets, 3.5 gpf was considered low flow (1).
Toilet have traditionally been a target for replacement because of the low flows associated with flushing. Even though low-flow (1.6 gpf) toilets have been the standard for some time, some places may still have older toilets and new technologies, such as dual-flush toilets that permit the user to select from two flush volumes depending on need, may lead to continued opportunities for improvements. A program began in 1992 to replace toilets in public buildings in San Diego, CA, was estimate to reduce water use by 8.5 MG/yr by the end of a decade.
(1) Maddaus, W. O. (1990). Integrating water conservation into total water management. Journal AWWA. 82(_): 12-13.